Genotype-Phenotype Correlations in Neurofibromatosis and Their Potential Clinical Use

Tumors of the nervous system and hearing loss: Beyond vestibular schwannomas

Hearing loss is a common side effect of many tumor treatments. However, hearing loss can also occur as a direct result of certain tumors of the nervous system, the most common of which are the vestibular schwannomas (VS). These tumors arise from Schwann cells of the vestibulocochlear nerve and their main cause is the loss of function of NF2, with 95 % of cases being sporadic and 5 % being part of the rare neurofibromatosis type 2 (NF2)-related Schwannomatosis. Genetic variations in NF2 do not fully explain the clinical heterogeneity of VS, and interactions between Schwann cells and their microenvironment appear to be critical for tumor development. Preclinical in vitro and in vivo models of VS are needed to develop prognostic biomarkers and targeted therapies. In addition to VS, other tumors can affect hearing. Meningiomas and other masses in the cerebellopontine angle can compress the vestibulocochlear nerve due to their anatomic proximity. Gliomas can disrupt several neurological functions, including hearing; in fact, glioblastoma multiforme, the most aggressive subtype, may exhibit early symptoms of auditory alterations. Besides, treatments for high-grade tumors, including chemotherapy or radiotherapy, as well as incomplete resections, can induce long-term auditory dysfunction. Because hearing loss can have an irreversible and dramatic impact on quality of life, it should be considered in the clinical management plan of patients with tumors, and monitored throughout the course of the disease.

The Australian Traumatic Brain Injury Initiative: Statement of Working Principles and Rapid Review of Methods to Define Data Dictionaries for Neurological Conditions

The Australian Traumatic Brain Injury Initiative (AUS-TBI) aims to develop a health informatics approach to collect data predictive of outcomes for persons with moderate-severe TBI across Australia. Central to this approach is a data dictionary; however, no systematic reviews of methods to define and develop data dictionaries exist to-date. This rapid systematic review aimed to identify and characterize methods for designing data dictionaries to collect outcomes or variables in persons with neurological conditions. Database searches were conducted from inception through October 2021. Records were screened in two stages against set criteria to identify methods to define data dictionaries for neurological conditions (International Classification of Diseases, 11th Revision: 08, 22, and 23). Standardized data were extracted. Processes were checked at each stage by independent review of a random 25% of records. Consensus was reached through discussion where necessary. Thirty-nine initiatives were identified across 29 neurological conditions. No single established or recommended method for defining a data dictionary was identified. Nine initiatives conducted systematic reviews to collate information before implementing a consensus process. Thirty-seven initiatives consulted with end-users. Methods of consultation were "roundtable" discussion (n = 30); with facilitation (n = 16); that was iterative (n = 27); and frequently conducted in-person (n = 27). Researcher stakeholders were involved in all initiatives and clinicians in 25. Importantly, only six initiatives involved persons with lived experience of TBI and four involved carers. Methods for defining data dictionaries were variable and reporting is sparse. Our findings are instructive for AUS-TBI and can be used to further development of methods for defining data dictionaries.

Genotype-phenotype correlations of neurofibromatosis type 1: a cross-sectional study from a large Chinese cohort

BACKGROUND

Neurofibromatosis type 1 (NF1) is a highly heterogeneous autosomal genetic disorder characterized by a broad spectrum of clinical and molecular manifestations. The correlations between genotype and phenotype in NF1 remain elusive. This study aimed to elucidate genotype-phenotype associations in a large Chinese cohort of NF1 patients.

METHODS

We included NF1 patients from our center who underwent genetic testing for NF1 variants and systemic examination. Genotype-phenotype correlation analyses were performed, focusing on variation types and involved neurofibromin domains.

RESULTS

A total of 195 patients were enrolled, comprising 105 males and 90 females, with a median age of 18 years. Truncating variants, single amino acid variations, and splicing variants accounted for 139/195 (71.3%), 23/195 (11.8%), and 33/195 (16.9%), respectively. Patients with splicing variants exhibited a significantly higher prevalence of spinal plexiform neurofibromas (spinal PNF) than those with truncating variants (76.4% vs. 51.8%; p = 0.022). Variations affecting the PKC domain were associated with higher rates of cutaneous neurofibromas (CNF) (100% vs. 64.9%, p < 0.001), Lisch nodules (100% vs. 61.2%, p < 0.001), plexiform neurofibromas (PNF) (100% vs. 95.7%, p = 0.009), and psychiatric disorders (11.8% vs. 1.6%, p = 0.042). Patients with mutations in the CSRD had an elevated risk of secondary primary malignancies (11.6% vs. 2.8%, p = 0.015). GRD involvement might enhance the risk of Lisch nodules (76.9% vs. 53.7%, p = 0.044). Variations in the Sec14-PH domain were correlated with a higher rate of CNF (76.8% vs. 58.6%, p = 0.014). Additionally, we found that the p.R1748* variants carry a high risk of malignancy.

CONCLUSION

Our study suggested some novel genotype-phenotype correlations within a Chinese cohort, providing innovative insights into this complex field that may contribute to genetic counseling, risk stratification, and clinical management for the NF1 population.

Global research trends in cutaneous neurofibromas: A bibliometric analysis from 2003 to 2022

BACKGROUND

Neurofibromatosis type 1 (NF1) is a common inherited disorder characterized by cutaneous neurofibromas and other features. It is still a challenge in managing inoperable patients and the complex nature of the disease. Bibliometric analyses for cutaneous neurofibromas (cNF) could offer insights into impactful research and collaborations, guiding future efforts to improve patient care and outcomes.

METHODS

We conducted a comprehensive literature search of the Web of Science Core Collection database for the period 2003-2022. Data processing and analysis were performed using bibliometric tools including VOSviewer, CiteSpace, and "Bibliometrix" package. Our analysis assessed the publication or collaboration of countries, institutions, authors, and journals, as well as the co-citation and burst of references and keywords.

RESULTS

The analysis included 927 articles from 465 journals and 1402 institutions in 67 countries. Research on cNF has been increasing in recent years. The United States leads the field. Pierre Wolkenstein was the top author, while The University of Hamburg was the most productive institution. The American Journal of Medical Genetics Part A published the most articles in cNF. Co-citation analysis revealed major research topics and trends over time, showing growing interest in evaluating quality of life and genotype-phenotype correlation for cNF patients. Emerging topical MEK inhibitors show potential as a promising therapy.

CONCLUSION

In conclusion, our bibliometric analysis of cNF research over the past two decades highlights the growing interest in this complex genetic disorder. Leading countries, authors, institutions, and journals have played significant roles in shaping the field. Notably, recent trends emphasize the importance of evaluating quality of life and genotype-phenotype correlations in cNF patients. Furthermore, the emergence of promising topical therapy marks an exciting development in the quest to improve patient care and outcomes for those affected by cNF, paving the way for future research and collaboration.

Neurofibromatosis type 1: Clinical characteristics and mutation spectrum in a North Indian cohort

Background

Neurofibromatosis type 1 (NF1) is a unique, highly penetrant neuro-cutaneous disorder with a wide range of manifestations. Though the clinical diagnosis of NF1 is straight forward, there can be other disorders which mimic NF1, especially its cutaneous features. Here we describe the clinical and mutation spectrum of a series of individuals whose primary diagnosis was NF1 or NF1 related disorders.

Methods

We have screened 29 unrelated individuals who fulfilled the clinical criteria of NF1. Whole exome sequencing (WES) was done in all individuals except one with suspected microdeletion syndrome with NF1 in whom Cytogenetic microarray (CMA) was done.

Results

Out of 29 suspected patients, 25 had germline pathogenic/likely pathogenic variants involving NF1 gene. Five novel and 20 known variants in coding and non-coding regions were identified, among them 7 variants were deletions (28%), 7 nonsense (28%), 3 splice-site (12%), 4 missense (16%), 2 duplications (8%) and 2 (8%) were contiguous deletions. In those where NF1 variants were not detected, 3 had neurofibromatosis type 2 (NF2) and 1 rare autosomal recessive form of Elher Danlos syndrome.

Conclusion

We hereby present the wide range of manifestations in different age groups and the mutation spectrum ranging from small scale variants to contiguous gene deletion syndromes involving NF1 gene. We highlight the usefulness of molecular testing and its importance in tumor surveillance and genetic counseling in this disorder.

Long-term outcomes of stereotactic radiosurgery for intracranial schwannoma in neurofibromatosis type 2: a genetic analysis perspective

PURPOSE

Neurofibromatosis type 2 (NF2) is intractable because of multiple tumors involving the nervous system and is clinically diverse and genotype-dependent. Stereotactic radiosurgery (SRS) for NF2-associated schwannomas remains controversial. We aimed to investigate the association between radiosurgical outcomes and mutation types in NF2-associated schwannomas.

METHODS

This single-institute retrospective study included consecutive NF2 patients with intracranial schwannomas treated with SRS. The patients' types of germline mutations ("Truncating," "Large deletion," "Splice site," "Missense," and "Mosaic") and Halliday's genetic severity scores were examined, and the associations with progression-free rate (PFR) and overall survival (OS) were analyzed.

RESULTS

The study enrolled 14 patients with NF2 with 22 associated intracranial schwannomas (median follow-up, 102 months).　The PFRs in the entire cohort were 95% at 5 years and 90% at 10-20 years. The PFRs tended to be worse in patients with truncating mutation exons 2-13 than in those with other mutation types (91% at 5 years and 82% at 10-20 years vs. 100% at 10-20 years, P = 0.140). The OSs were 89% for patients aged 40 years and 74% for those aged 60 years in the entire cohort and significantly lower in genetic severity group 3 than in the other groups (100% vs. 50% for those aged 35 years; P = 0.016).

CONCLUSION

SRS achieved excellent PFR for NF2-associated intracranial schwannomas in the mild (group 2A) and moderate (group 2B) groups. SRS necessitates careful consideration for the severe group (group 3), especially in cases with NF2 truncating mutation exons 2-13.

A new era for myelin research in Neurofibromatosis type 1

Evidence for myelin regulating higher-order brain function and disease is rapidly accumulating; however, defining cellular/molecular mechanisms remains challenging partially due to the dynamic brain physiology involving deep changes during development, aging, and in response to learning and disease. Furthermore, as the etiology of most neurological conditions remains obscure, most research models focus on mimicking symptoms, which limits understanding of their molecular onset and progression. Studying diseases caused by single gene mutations represents an opportunity to understand brain dys/function, including those regulated by myelin. Here, we discuss known and potential repercussions of abnormal central myelin on the neuropathophysiology of Neurofibromatosis Type 1 (NF1). Most patients with this monogenic disease present with neurological symptoms diverse in kind, severity, and onset/decline, including learning disabilities, autism spectrum disorders, attention deficit and hyperactivity disorder, motor coordination issues, and increased risk for depression and dementia. Coincidentally, most NF1 patients show diverse white matter/myelin abnormalities. Although myelin-behavior links were proposed decades ago, no solid data can prove or refute this idea yet. A recent upsurge in myelin biology understanding and research/therapeutic tools provides opportunities to address this debate. As precision medicine moves forward, an integrative understanding of all cell types disrupted in neurological conditions becomes a priority. Hence, this review aims to serve as a bridge between fundamental cellular/molecular myelin biology and clinical research in NF1.

Parent perspectives on disclosing a pediatric neurofibromatosis type 1 diagnosis

Neurofibromatosis 1 (NF1) is a common genetic disorder typically diagnosed in childhood and characterized by cutaneous findings, nerve sheath tumors, skeletal abnormalities, malignancies, and developmental differences. Due to its variability, NF1 is an unpredictable condition that parents have concerns about discussing with their children. While there are publications addressing the disclosure of genetic conditions in general, no NF1-specific disclosure literature exists. To fill this gap, this mixed methods study sought to evaluate the concerns, barriers, failures, or successes parents or guardians have experienced when they have or have not chosen to tell their child(ren) about an NF1 diagnosis. Parents of children between ages 0 and 17 with a diagnosis of NF1 completed a survey and some parents were selected for an interview invitation. A total of 258 surveys were completed, and 20 parents were interviewed. Interview transcripts were categorized into disclosure and non-disclosure groups. Themes were organized into five categories based on interview questions: disclosure concerns, factors affecting disclosure/non-disclosure, approaches to disclosure, desired resources, and recommendations for disclosure. Sentiment analysis was performed on responses about the disclosure discussion itself. Results indicated that most parents (70.5%) disclosed the NF1 diagnosis to their child and overall felt it was a positive experience. Almost one-third of parents (29.5%) had not disclosed the diagnosis. A strong significance was identified between disclosure and severe presentation of NF1 (p = 0.0008). Parents in both groups shared similar concerns about discussing the diagnosis and multiple factors influenced the disclosure decision. Most parents approached disclosure as a process and emphasized the need to be honest and supportive of their child. Parents highlighted the need for more educational resources for children and guidance on how to disclose. These findings indicate that additional resources and support for parents would facilitate disclosure and the involvement of genetic counselors in the process would be beneficial.

Insights into Novel Choroidal and Retinal Clinical Signs in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a rare inherited neurocutaneous disorder with a major impact on the skin, nervous system and eyes. The ocular diagnostic hallmarks of this disease include iris Lisch nodules, ocular and eyelid neurofibromas, eyelid café-au-lait spots and optic pathway gliomas (OPGs). In the last years, new manifestations have been identified in the ocular district in NF1 including choroidal abnormalities (CAs), hyperpigmented spots (HSs) and retinal vascular abnormalities (RVAs). Recent advances in multi-modality imaging in ophthalmology have allowed for the improved characterization of these clinical signs. Accordingly, CAs, easily detectable as bright patchy nodules on near-infrared imaging, have recently been added to the revised diagnostic criteria for NF1 due to their high specificity and sensitivity. Furthermore, subclinical alterations of the visual pathways, regardless of the presence of OPGs, have been recently described in NF1, with a primary role of neurofibromin in the myelination process. In this paper, we reviewed the latest progress in the understanding of choroidal and retinal abnormalities in NF1 patients. The clinical significance of the recently revised diagnostic criteria for NF1 is discussed along with new updates in molecular diagnosis. New insights into NF1-related neuro-ophthalmic manifestations are also provided based on electrophysiological and optical coherence tomography (OCT) studies.

Comprehensive neurological evaluation of a cohort of patients with neurofibromatosis type 1 from a single institution

Neurofibromatosis type 1 (NF1) is a phenotypically heterogenous multisystem cancer predisposition syndrome manifesting in childhood and adolescents. Central nervous system (CNS) manifestations include structural, neurodevelopmental, and neoplastic disease. We aimed to (1) characterize the spectrum of CNS manifestations of NF1 in a paediatric population, (2) explore radiological features in the CNS by image analyses, and (3) correlate genotype with phenotypic expression for those with a genetic diagnosis. We performed a database search in the hospital information system covering the period between January 2017 and December 2020. We evaluated the phenotype by retrospective chart review and imaging analysis. 59 patients were diagnosed with NF1 [median age 10.6 years (range, 1.1-22.6); 31 female] at last follow-up, pathogenic NF1 variants were identified in 26/29. 49/59 patients presented with neurological manifestations including 28 with structural and neurodevelopmental findings, 16 with neurodevelopmental, and 5 with structural findings only. Focal areas of signal intensity (FASI) were identified in 29/39, cerebrovascular anomalies in 4/39. Neurodevelopmental delay was reported in 27/59 patients, learning difficulties in 19/59. Optic pathway gliomas (OPG) were diagnosed in 18/59 patients, 13/59 had low-grade gliomas outside the visual pathways. 12 patients received chemotherapy. Beside the established NF1 microdeletion, neither genotype nor FASI were associated with the neurological phenotype. NF1 was associated with a spectrum of CNS manifestations in at least 83.0% of patients. Regular neuropsychological assessment complementing frequent clinical and ophthalmologic testing for OPG is necessary in the care of each child with NF1.

A systematic review of targeted therapy for vestibular schwannoma in patients with NF2-related schwannomatosis

Background

One of the hallmarks of NF2-related Schwannomatosis (NF2-related SWN) is bilateral vestibular schwannomas (VS) that can cause progressive hearing impairment in patients. This systematic review was performed to investigate the efficacy and toxicity of tested targeted agents.

Methods

The systematic search was conducted on PubMed and EMBASE Ovid databases from inception to October 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The incidence of outcomes in studies involving bevacizumab and other targeted therapies was extracted. The bevacizumab results were pooled, and 95% confidence intervals (95% CI) were calculated.

Results

Sixteen studies (8 prospective and 8 retrospective) testing 6 drugs were selected out of 721 search results. There were 10 studies concerning bevacizumab, with a total of 200 patients. The pooled radiographic response rate (RR) was 38% (95% CI: 31 - 45%) and the pooled hearing response rate (HR) was 45% (95% CI: 36 - 54%). The most frequent bevacizumab-related toxicities were hypertension and menorrhagia. Of other targeted therapies showing activity, lapatinib had a RR of 6% and a HR of 31%. A VEGFR vaccine showed RR in 29% and HR in 40% of patients. Both agents had a manageable safety profile.

Conclusions

Bevacizumab, in comparison to other targeted agents, showed the highest efficacy. Lower dosage of bevacizumab shows comparable efficacy and may reduce toxicity. Other targeted agents, administered alone or as combination therapy, have the potential to improve outcomes for VS in patients with NF2-related SWN, but future clinical studies are needed.

A systematic review and meta-analysis of intellectual, neuropsychological, and psychoeducational functioning in neurofibromatosis type 1

Neurofibromatosis Type 1 (NF1) is a common genetic disorder frequently associated with cognitive deficits. Despite cognitive deficits being a key feature of NF1, the profile of such impairments in NF1 has been shown to be heterogeneous. Thus, we sought to quantitatively synthesize the extant literature on cognitive functioning in NF1. A random-effects meta-analysis of cross-sectional studies was carried out comparing cognitive functioning of patients with NF1 to typically developing or unaffected sibling comparison subjects of all ages. Analyses included 50 articles (Total N_NF1 = 1,522; M_Age = 15.70 years, range = 0.52-69.60), yielding 460 effect sizes. Overall moderate deficits were observed [g = -0.64, 95% CI = (-0.69, -0.60)] wherein impairments differed at the level of cognitive domain. Deficits ranged from large [general intelligence: g = -0.95, 95% CI = (-1.12, -0.79)] to small [emotion: g = -0.37, 95% CI = (-0.63, -0.11)]. Moderation analyses revealed nonsignificant contributions of age, sex, educational attainment, and parental level of education to outcomes. These results illustrate that cognitive impairments are diffuse and salient across the lifespan in NF1. Taken together, these results further demonstrate efforts should be made to evaluate and address cognitive morbidity in patients with NF1 in conjunction with existing best practices.

Current concepts of neurofibromatosis type 1: pathophysiology and treatment

Neurofibromatosis type 1 is the most common tumor predisposition syndrome inherited in an autosomal dominant (100% penetrance) fashion with a wide variety of expressivity. From the perspective of plastic surgery, the most significant clinical symptoms, including disfiguration, peripheral neurologic symptoms, and skeletal abnormalities, are caused by various tumors originating from the affected nerves. Surgical removal is the standard of care for these tumors. However, the outcome is frequently unsatisfactory, facilitating the search for additional therapeutic adjuvants. Current trials of molecularly targeted therapies are promising.

Delineating the autistic phenotype in children with neurofibromatosis type 1

Background

Existing research has demonstrated elevated autistic behaviours in children with neurofibromatosis type 1 (NF1), but the autistic phenotype and its relationship to other neurodevelopmental manifestations of NF1 remains unclear. To address this gap, we performed detailed characterisation of autistic behaviours in children with NF1 and investigated their association with other common NF1 child characteristics.

Methods

Participants were drawn from a larger cross-sectional study examining autism in children with NF1. The population analysed in this study scored above threshold on the Social Responsiveness Scale-Second Edition (T-score ≥ 60; 51% larger cohort) and completed the Autism Diagnostic Interview-Revised (ADI-R) and/or the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2). All participants underwent evaluation of their intellectual function, and behavioural data were collected via parent questionnaires.

Results

The study cohort comprised 68 children (3–15 years). Sixty-three per cent met the ADOS-2 ‘autism spectrum’ cut-off, and 34% exceeded the more stringent threshold for ‘autistic disorder’ on the ADI-R. Social communication symptoms were common and wide-ranging, while restricted and repetitive behaviours (RRBs) were most commonly characterised by ‘insistence on sameness’ (IS) behaviours such as circumscribed interests and difficulties with minor changes. Autistic behaviours were weakly correlated with hyperactive/impulsive attention deficit hyperactivity disorder (ADHD) symptoms but not with inattentive ADHD or other behavioural characteristics. Language and verbal IQ were weakly related to social communication behaviours but not to RRBs.

Limitations

Lack of genetic validation of NF1, no clinical diagnosis of autism, and a retrospective assessment of autistic behaviours in early childhood.

Conclusions

Findings provide strong support for elevated autistic behaviours in children with NF1. While these behaviours were relatively independent of other NF1 comorbidities, the importance of taking broader child characteristics into consideration when interpreting data from autism-specific measures in this population is highlighted. Social communication deficits appear similar to those observed in idiopathic autism and are coupled with a unique RRB profile comprising prominent IS behaviours. This autistic phenotype and its relationship to common NF1 comorbidities such as anxiety and executive dysfunction will be important to examine in future research. Current findings have important implications for the early identification of autism in NF1 and clinical management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00481-3.

Natural history of NF1 c.2970_2972del p.(Met992del): confirmation of a low risk of complications in a longitudinal study

Individuals with the three base pair deletion NM_000267.3(NF1):c.2970_2972del p.(Met992del) have been recognised to present with a milder neurofibromatosis type 1 (NF1) phenotype characterised by café-au-lait macules (CALs) and intertriginous freckling, as well as a lack of cutaneous, subcutaneous and plexiform neurofibromas and other NF1-associated complications. Examining large cohorts of patients over time with this specific genotype is important to confirm the presentation and associated risks of this variant across the lifespan. Forty-one individuals with the in-frame NF1 deletion p.Met992del were identified from 31 families. Clinicians completed a standardised clinical questionnaire for each patient and the resulting data were collated and compared to published cohorts. Thirteen patients have been previously reported, and updated clinical information has been obtained for these individuals. Both CALs and intertriginous freckling were present in the majority of individuals (26/41, 63%) and the only confirmed features in 11 (27%). 34/41 (83%) of the cohort met NIH diagnostic criteria. There was a notable absence of all NF1-associated tumour types (neurofibroma and glioma). Neurofibroma were observed in only one individual—a subcutaneous lesion (confirmed histologically). Nineteen individuals were described as having a learning disability (46%). This study confirms that individuals with p.Met992del display a mild tumoural phenotype compared to those with ‘classical’, clinically diagnosed NF1, and this appears to be the case longitudinally through time as well as at presentation. Learning difficulties, however, appear to affect a significant proportion of NF1 subjects with this phenotype. Knowledge of this genotype–phenotype association is fundamental to accurate prognostication for families and caregivers.

Novel germinal mutation in NF1: case report

BACKGROUND

Neurofibromatosis 1 is a systemic pathology that predominantly affects the central and peripheral nervous system and the skin, although it can potentially affect any organ of the human body. The NF1 gene (Neurofibromatosis 1) is located on chromosome 17q11.2, a gene of great length that encodes neurofibromin, a protein with a tumor suppressor function with a functional mechanism that is not clearly known.

METHODS

We reviewed the medical records, radiologic images, genetic studies, and clinical photographs of a patient with confirmed diagnosis of Neurofibromatosis 1 who was attended in our center between 2012 and 2021. The clinical course, the applied therapeutics and genetic findings were assessed.

RESULTS

We present the case of a 10-year-old patient with a clinical diagnosis of neurofibromatosis type 1 (more than 6 coffee-with-milk spots, axillary ephelides, a cutaneous xanthogranuloma and hyperhidrosis) in whom a c.6255delG mutation (pMet2085IlefsTer2) in exon 42 of the NF1 gene was detected. There was no family history of diagnosed NF1. Neuroimaging studies showed myelin vacuolization in the posterior fossa, in dentate nucleus, midbrain and both globus pallidus. These findings showed stability over time. The patient is now asymptomatic and under evolutionary follow-up.

CONCLUSIONS

The mutation shown here has not been previously described. Reports of previously unknown mutations are an important source of knowledge that can contribute to improved genetic diagnosis and a better understanding of the pathophysiological and genetic characteristics of diseases.

Recurrent NF1 gene variants and their genotype/phenotype correlations in patients with Neurofibromatosis type I

Neurofibromatosis type I, a genetic condition due to pathogenic variants in the NF1 gene, is burdened by a high rate of complications, including neoplasms, which increase morbidity and mortality for the disease. We retrospectively re-evaluated the NF1 gene variants found in the period 2000-2019 and we studied for genotype/phenotype correlations of disease complications and neoplasms 34 variants, which were shared by at least two unrelated families (range 2-11) for a total 141 of probands and 21 relatives affected by Neurofibromatosis type I. Recurrent variants could be ascribed to the most common mutational mechanisms (C to T transition, microsatellite slippage, non-homologous recombination). In genotype/phenotype correlations, the variants p.Arg440*, p.Tyr489Cys, and p.Arg1947*, together with the gross gene deletions, displayed the highest rates of complications. When considering neoplasms, carriers of variants falling in the extradomain region at the 5' end of NF1 had a lower age-related cancer frequency than the rest of the gene sequence, showing a borderline significance (p = 0.045), which was not conserved after correction with covariates. We conclude that (1) hotspots in NF1 occur via different mutational mechanisms, (2) several variants are associated with high rates of complications and cancers, and (3) there is an initial evidence toward a lower cancer risk for carriers of variants in the 5' end of the NF1 gene although not significant at the multivariate analysis.